【作者】 郭风琪；

【导师】 余志武；

【作者基本信息】 中南大学 ， 结构工程， 2012， 博士

【摘要】 石拱桥是一种古老的桥型,在我国应用广泛,据统计,我国现存石拱桥的数量就达四百多万座。由于自然环境、超载、设计、施工、自然灾害等因素的影响,导致石拱桥损坏现象极其严重,甚至导致坍塌。对在役石拱桥的评估、维护、加固、设计等关键技术体系和方法进行系统的研究有很强的现实意义,全文主要工作内容如下：1.在研究石砌体损伤机理的基础上,提出了相应的石砌体损伤模型。应用二参数Weibull分布描述损伤变量,引入峰值割线模量参数,推导并建立了石砌体的通用本构关系公式。该公式使石砌体整个压缩过程中的应力应变关系采用单一表达式描述,形式简单,参数少,且连续可导,便于实际应用,能较好符合实测应力应变关系。2.基于Ansys建立了大跨石拱桥的空间实体有限元模型,应用本文所建立的石砌体应力应变关系,对该桥的几何非线性、双重非线性及受损伤后的石拱桥的极限承载力进行了研究。全面分析了石拱桥在各种荷载工况、不同设计参数以及初始几何缺陷和损伤情况下的极限承载力变化规律和破坏形态,为在役石拱桥的评估与加固提供了理论指导。3.针对不同场地的典型地震波和基于规范生成的人工波,对石拱桥的地震动反应进行了分析,讨论了不同拱轴线和矢跨比对石拱桥抗震性能的影响。基于工程实例,进行了石拱桥的抗震加固方法的分析和对比,提出了提载情况下石拱桥抗震加固的优选方法。4.针对损伤识别训练样本庞大,低效的问题,提出了石拱桥的子结构识别的概念。通过检测手段和数学方法的结合,引入固有频率和静力位移为组合参数,建立了基于概率神经网络PNN的石拱桥子结构损伤识别方法,为石拱桥的监测和评估提供了可靠的数学方法。5.基于可靠度理论,引入时变可靠度理论,针对常见的石拱桥加固方法,提出了加固后的石拱桥组合截面抗力变化的概念,分析了荷载效应和结构抗力随时间变化的情况,建立了石拱桥加固后寿命预测的方法。对桥梁养护决策进行了分析,提出了基于马尔科夫过程的石拱桥加固后最优维护策略判断方法。根据结构所处的不同状态安排相应的最优维护策略,节省了维护费用,为加固维护决策提供了科学的依据。更多还原

【Abstract】 As an old bridge type, stone arch bridge is widely used in China. According to statistics, the number of existing stone arch bridges have reached four million seats. Because of natural environment, overloading, design, construction, natural disasters and other factors, stone arch bridges have been seriously damaged, and even collapsed. So it is of great practical significance to carry out systematic research work on assessment, maintenance, reinforcement, design and other key technical system and method for in-service stone arch bridge. Main works are as follows:1. The corresponding damage model was presented based on study of damage mechanism of stone masonry, Two-parameter Weibull parameters were used to describe damage variable and by introducing the peak secant modulus a general constitutive equation was derived and established. Then the stress-strain relationship during the whole compression process could be expressed by a single expression. It was of simple form and less parameters. It was continuous derivable, easy to practice, and better meet the actual stress-strain relationship.2. The spatial entity finite element model of long-span stone arch bridge was built based on Ansys. The geometric nonlinearity, double nonlinear and ultimate bearing capacity of injured stone arch bridge were studied, using established stress-strain relationship. The variation of ultimate bearing capacity and failure modes were comprehensively analyzed for stone arch bridge in a variety of load conditions, different design parameters and initial geometric imperfections and damage. It provided theoretical guidance for the assessment and reinforcement of in-service stone arch bridge.3. The analysis on ground motion response of stone arch bridge was done according to typical seismic waves in different site and specification-based artificial waves. The effects of different arch axis and rise-span ratio on seismic behavior of stone arch bridge were discussed. Based on engineering practice, the analysis and comparison of seismic reinforcement methods of stone arch bridge were carried out and the preferred method of seismic reinforcement was put forward for increasing carrying capacity for stone arch bridge.4. In view of huge damage identification training samples and inefficient problem, the concept of sub-structure identification of stone arch bridge was proposed. With the combination of detecting means and mathematical methods, by introducing natural frequency and static displacement as combined parameter, sub-structure damage identification method based on probabilistic neural network PNN was established. It provided a reliable mathematical method for monitoring and evaluation of stone arch bridge.5.Based on reliability theory, by introducing the theory of time-varying reliability, aiming at common reinforcement methods of stone arch bridge, the concept of resistance varying of composite section of stone arch bridge was proposed, the changes of load effect and structural resistance with time were analyzed and life prediction method after reinforcement was built. Bridge maintenance decisions were analyzed and the optimal maintenance strategy judging method based on Markov process was given for reinforced stone arch bridge. Ihe optimal maintenance strategy was arranged according to different states. It saved cost and provided scientific basis for the reinforcement and maintenance.更多还原